Simon Menner's photographs demonstrate how unreliable our eyes actually are. Find out where the sniper is at the bottom of this article. Photograph: Simon Menner

If you think you have 20/20 vision, think again. Camouflage works by exploiting the weaknesses of human perception. Most of us rely on our eyesight as our first and best guide to the world around us – Leonardo da Vinci claimed it is worse to lose your sight than any of your other senses because we orient ourselves visually.

Yet these pictures by Simon Menner demonstrate how unreliable our eyes actually are. They show snipers hiding in a variety of landscapes. Would you notice any of them without the red circles locating their whereabouts? Can you even see them with the aid of the prompts?

This is simple scientific trickery. Our brains just don't decode visual information as efficiently as we think they do. A broken pattern, or a confusion of depth and flatness caused by illusory shadows, or just a subtle blending of colours can make the visible invisible. Designers of camouflage have been researching and exploiting such optical illusions since the first world war – yet another reason to mark the centenary of its outbreak. One of the first uses of camouflage in 1914-18 was to disguise dreadnought battleships by painting them with giant Futurist markings to shatter their outlines in the water. A century on, the art of disguise has – these pictures prove – become a lot more subtle than such early efforts.

So subtle, in fact, that these invisible snipers are just the beginning of a strange age of human ethereality. Designers are working right now on a Harry Potter style "invisibility cloak" that can be 3D printed. The principles of camouflage can be translated to a nano scale by such technology, confusing the mind at a microscopic level.

It's just another step in humanity's imitation of the inborn skills of other animals through technology. Just as we learned to fly in emulation of birds, the art of camouflage is copied from reptiles and insects whose broken coloured patterns fit into the vegetation around them. Beware the sniper in the grass.